Vitamin A

Vitamin A is a fat-soluble vitamin that accumulates in the liver. It plays several key roles in the body:

• Helps with night vision
• Maintains healthy tissues (skin, mucous membranes)
• Contributes to the development and growth of teeth and bones
• Maintains good immune function
• Acts as an antioxidant

Other names

• Retinol
• Beta-carotene
• Carotenoids

Sources

Liver is the richest dietary source of vitamin A, followed by fruit, vegetables, and dairy products.

Animal-source foods contain the active form of vitamin A, retinol. Plant-source foods contain carotenoids, the pigments that give many fruits and vegetables their yellow and orange colour. Some of these carotenoids, including beta-carotene, are converted by the body into vitamin A.

Recommended Daily Allowance (RDA)

The RDA for vitamine A is the daily vitamine A intake required to meet the needs of most healthy individuals.

Deficiency

Deficiencies are usually uncommon, as the liver can store vitamin A for long periods. However, deficiencies do occur throughout the world, mainly in cases of malnutrition and poverty, and among children in developing countries.

Certain malabsorption problems and liver disease can also lead to a vitamin A deficiency. Symptoms include the following:

• Night blindness
• Dry cornea, which can lead to blindness
• Dry skin and hair
• Weaker resistance to infection
• Slowed growth in children

Toxicity

Unless you eat a lot of liver, it's virtually impossible to get too much vitamin A from your diet alone. Furthermore, the carotenoids found in food are non-toxic, even when consumed in large quantities, as the body converts them into vitamin A very slowly. A yellow discoloration of the skin, a rare and harmless side effect, may occur if you consume excessive carotenoids (e.g., beta-carotene).

Taking fish liver oil supplements or other supplement formulations can result in toxic levels of vitamin A. The main signs and symptoms of vitamin A toxicity are as follows:

• Headaches, loss of appetite, and weakness
• Nausea and vomiting
• Joint and bone pain and risk of fractures
• Dry skin and lips, hair loss, and brittle nails
• Liver, spleen, and eye problems
• Birth defects in a fetus

Supplements

Deficiencies are rare, and consuming too much vitamin A can be toxic. Supplements are therefore not recommended without consulting your health care provider.

Vitamin A supplements should not be taken with medications containing a synthetic form of vitamin A (retinoids), which are used to treat acne and psoriasis.

Always watch your diet: